Project description:The main avenue for the development of an HIV-1 vaccine remains the induction of protective antibodies. A rationale approach is to target antigen to specific receptors on dendritic cells (DC) via fused monoclonal antibodies (mAb). In mouse and non-human primate models, targeting of skin Langerhans cells (LC) with anti-Langerin mAbs fused with HIV-1 Gag antigen drives antigen-specific humoral responses. The development of these immunization strategies in humans requires a better understanding of early immune events driven by human LC. We therefore produced anti-Langerin mAbs fused with the HIV-1 gp140z Envelope (αLC.Env). First, we show that primary skin human LC and in vitro differentiated LC induce differentiation and expansion of naïve CD4+ T cells into T follicular helper (Tfh) cells. Second, when human LC are pre-treated with αLC.Env, differentiated Tfh cells significantly promote the production of specific IgG by B cells. Strikingly, HIV-Env-specific Ig are secreted by HIV-specific memory B cells. Consistently, we found that receptors and cytokines involved in Tfh differentiation and B cell functions are upregulated by LC during their maturation and after targeting Langerin. Finally, we show that subcutaneous immunisation of mice by αLC.Env induces germinal center (GC) reaction in draining lymph nodes with higher numbers of Tfh cells, Env-specific B cells, as well as specific IgG serum levels compared to mice immunised with the non-targeting Env antigen. Altogether, we provide evidence that human LC properly targeted may be licensed to efficiently induce Tfh cell and B cell responses in GC.
Project description:The main avenue for the development of an HIV-1 vaccine remains the induction of protective antibodies. A rationale approach is to target antigen to specific receptors on dendritic cells (DC) via fused monoclonal antibodies (mAb). In mouse and non-human primate models, targeting of skin Langerhans cells (LC) with anti-Langerin mAbs fused with HIV-1 Gag antigen drives antigen-specific humoral responses. The development of these immunization strategies in humans requires a better understanding of early immune events driven by human LC. We therefore produced anti-Langerin mAbs fused with the HIV-1 gp140z Envelope (αLC.Env). First, we show that primary skin human LC and in vitro differentiated LC induce differentiation and expansion of naïve CD4+ T cells into T follicular helper (Tfh) cells. Second, when human LC are pre-treated with αLC.Env, differentiated Tfh cells significantly promote the production of specific IgG by B cells. Strikingly, HIV-Env-specific Ig are secreted by HIV-specific memory B cells. Consistently, we found that receptors and cytokines involved in Tfh differentiation and B cell functions are upregulated by LC during their maturation and after targeting Langerin. Finally, we show that subcutaneous immunization of mice by αLC.Env induces germinal center (GC) reaction in draining lymph nodes with higher numbers of Tfh cells, Env-specific B cells, as well as specific IgG serum levels compared to mice immunized with the non-targeting Env antigen. Altogether, we provide evidence that human LC properly targeted may be licensed to efficiently induce Tfh cell and B cell responses in GC.
Project description:Modified vaccinia virus Ankara (MVA) has been explored as a vaccine vector for use against infectious diseases and cancer. MVA is an immunogenic, attenuated poxvirus capable of eliciting robust cellular and humoral responses in pre-clinical animal models and in patients. However, upon infection with MVA, cells undergo rapid apoptosis leading to faster clearance of recombinant antigens. The fragmentation of the anti-apoptotic gene B13R in MVA could contribute to this effect. Here, we replaced the fragmented B13R with a functional version and observed that MVA-B13R infected HeLa cells and muscle cell lines delayed caspase 3 activation compared to MVA indicating slower progression of apoptosis. For immunogenicity studies, mice were intramuscularly immunized with recombinant MVA or MVA-B13R expressing SIV Gag, Pol and HIV Env (SHIV). We observed higher Env-specific humoral responses from MVA-B13R SHIV compared to MVA SHIV mice. To determine differences in the innate immune response that may have contributed to the augmented humoral response, we performed RNA-Seq analysis on draining lymph node cells after immunization. Gene set enrichment analysis from day 1 after immunization showed that MVA-B13R SHIV immunizations were associated with a negative enrichment for type I and II interferon responses compared to MVA SHIV mice indicating MVA-B13R SHIV induces a delayed anti-viral interferon response that may lead to the enhanced humoral response observed. Taken together, these results demonstrate that restoring B13R functionality in MVA significantly delays MVA-induced apoptosis, augments Env-specific antibody responses, and is associated with reduced interferon-alpha and interferon-gamma responses induced after vaccination.
Project description:Whole blood transcriptomics analysis of healthy individuals, immunized with the trivalent 2012-2013 season flu vaccine via transcutaneous, intramuscular or intradermal route. We define an early gene expression profile, detected at day 1 after immunization, that is associated with the development of either humoral or cytotoxic CD8 T cell responses. We used System Biology approach to analyse vaccine efficacy in order to find innate predictive biomarkers of the quality of adaptive responses for potential clinical use in the future. Moreover, from a methodological point of view this study increases knowledges on how vaccine route(s) can affect resulting immune responses and into mechanisms involved in the induction of humoral and cellular immunity to influenza vaccination.
Project description:The female reproductive tract is one of the major mucosal invasion site of HIV-1. This site has been neglected in previous HIV-1 vaccine studies. Immune responses in the female reproductive tract after systemic vaccination remain to be characterized. Using a modified vaccinia virus Ankara (MVA) as a vaccine model, we characterized specific immune responses in all compartments of the female reproductive tract (FRT) of non-human primates after systemic vaccination. Memory T cells were preferentially found in the lower tract (vagina and cervix), whereas antigen-presenting cells and innate lymphoid cells were mainly located in the upper tract (uterus and fallopian tubes). This compartmentalisation of immune cells in the FRT was supported by transcriptomic analyses and correlation network. Polyfunctional MVA-specific CD8+ T cells were detected in the blood, lymph nodes, vagina, cervix, uterus and fallopian tubes. Anti-MVA IgG and IgA were detected in cervicovaginal fluid after a second vaccine dose. Systemic vaccination with an MVA vector thus elicits cellular and antibody responses in the female reproductive tract.
Project description:Peptides generated by proteasome-catalyzed splicing of non-contiguous amino acid sequences have been shown to constitute a source of non-templated human leukocyte antigen class I (HLA-I) epitopes, but their role in pathogen-specific immunity remains unknown. CD8+ T cells are key mediators of human immunodeficiency virus type 1 (HIV-1) control, and identification of novel epitopes to enhance targeting of infected cells is a priority for prophylactic and therapeutic strategies. To explore the contribution of proteasome-catalyzed peptide splicing (PCPS) to HIV-1 epitope generation, we developed a broadly-applicable mass spectrometry-based discovery workflow that we employed to identify spliced HLA-I-bound peptides on HIV-infected cells. We demonstrate that HIV-1-derived spliced peptides comprise a novel, but relatively minor, component of the HLA-I-bound viral immunopeptidome. Although spliced HIV-1 peptides may elicit CD8+ T cell responses relatively infrequently during infection, CD8+ T cells primed by partially-overlapping contiguous epitopes in HIV-infected individuals were able to cross-recognize spliced viral peptides, suggesting a potential role for PCPS in restricting HIV-1 escape pathways. Vaccine-mediated priming of responses to spliced HIV-1 epitopes could thus provide a novel means of exploiting epitope targets typically under-utilized during natural infection.